Certain molecules when placed in contact with a surface can aggregate to form well-ordered two dimensional arrays. This process is called molecular self-assembly (MSA), and it is emerging as an important method to control the interactions between a surface and its environment (interfacial properties). Molecular self-assembly uses the fundamental forces between molecules (Van der Waals interactions, hydrophobic effects and hydrogen bonding) to form highly ordered macromolecular systems. This process has previously been used to synthesize molecular films on a variety of surfaces including gold (Bain and Whitesides (1988) Science 240:62-63), alumina (Holmes-Farley (1988) Langmuir 4:766-774), platinum (Soriaga and Hubbard (1982) J Am Chem Soc 104:3937-3945), and silicon (Maoz and Sagiv (1987) Langmuir 3:1045-1051) using commercially available alkylthiols, alkylsulfides, and organosilicon compounds.
Molecular films may be formed on solid supports by a variety of means including covalent attachment such as, for example, alkylsilanes to the surface oxide of silicon surfaces (Wasserman and Whitesides (1989) Langmuir 5:1074); by coordinating molecules such as alkylthiols on gold (Netzer et al (1982) Thin Solid Films 99:235-241); and by Langmuir-Blodgett (LB) methodology wherein molecules are held together by hydrophobic effects.
Simple chemical modifications of a monomeric subunit contained in a molecular film can lead to changes in the surface properties of the aggregated monomers. These films can be used to investigate and control the adhesive, recognition, wetting, electrochemical, and non-linear optical properties of the material's surface (Swalen et al (1987) Langmuir 3:932-950).
To date, general methods to synthesize materials with complex molecules, such as nucleic acids, peptides and carbohydrates, at the surface of films are non-existent.
It would be desirable to synthesize molecular films using functionalized molecules containing complex molecules such as, for example, ligands specific for biological receptors or enzymatic targets. It would also be desirable if these ligands could covalently or non-covalently bind to molecules and to a linker optionally having an internal polymerizable group capable of cross-linking to form polymerized films. Similarly, these monomers should be able to bind to surfaces non-covalently or covalently to generate these films. These materials could be used to detect molecular events at an interface comprising molecular recognition events and translate this information into an electrical or optical signal.